The patent application EP-A-0027321 describes a printing machine for variable format offset wherein have been provided two structures articulated rotationally about a shaft supporting the plate and printer rollers and a fixed structure on which the rubber-wrapped blanket is exchanged.
The European patent EP-A-1101611 relates to a device for supporting and exchanging in variable position with respect to the fixed position ink head, at least one of the plate, rubber-wrapped blanket and printer rollers in an offset printing press wherein the variable position elements are provided with arms which are rotatable about respective shafts, comprising the positioning means for positioning actuating means to rotate said support arms.
The European patent application EP-A-1 932 667 describes a printing machine for variable format offset wherein the offset inking head and the plate roller are integrated in a unit which is linearly or rotationally displaced together, separating it from the rubber-wrapped blanket roller, to allow changing said plate and rubber-wrapped blanket rollers and, if necessary, changing format.
The present application offers an alternative solution for changing format, based on printing groups configured as modular units provided to be operatively associated to a fixed position printing roller or drum, wherein the rubber-wrapped blanket roller, the plate roller and the offset inking head of each printing group are installed on respective support carriages displaced linearly.